How hitting a game cartridge unlocks gaming’s weirdest Easter egg

Here at Ars, we have a minor obsession with modern discoveries of Easter eggs from relatively ancient games. That includes a timing cue in Punch-Out!!, debug menus hidden in Mortal Kombatcabinets, and the first-ever Easter egg found in a game from 1977. But a Level Select Easter egg that involves physically hitting a Sonic 3D BlastGenesis cartridge—and the story behind it—is probably the weirdest such hidden feature we’ve ever heard of.

In a new video explanation, Traveller’s Tales founder Jon Burt, who worked on 3D Blast and a number of Sega games back in the ’90s, details how the unintended “smack the cartridge” Easter egg really grew out of an attempt to get around Sega’s onerous certification requirements for Genesis cartridges.

As Burt explains it, Sega’s certification process at the time took “a few weeks” and required re-submission for any failures, including crashes after the game was left running for days at a time. So Burt started catching any generalized, crash-worthy errors the game might trigger and disguising them as Easter eggs the player had stumbled on—such as a “secret time warp” that bounced the player around in Mickey Mania. As Burt recalls, “most things that were to crash the game just brought up the secret time warp, so Sega wouldn’t know it was actually a bug.”

For Sonic 3D Blast, Burt expanded this strategy to make use of a Vector table of all possible exceptions in the Genesis’ Motorola 68000 processor (PDF). Whenever the processor encountered any such unexpected error—such as a divide by zero issue—the game would simply redirect to the Level Select code. “That way, if I’d missed anything that would normally crash the game… instead of crashing, the level select would appear and we’d breeze through Sega’s submission process,” Burt says. “And it worked, and we did.”

Thus, when a player hits or wiggles the 3D Blast cartridge, the connection between the game and the console gets broken just long enough to throw a processor exception, which gets captured and thrown to the Level Select screen instead of causing a crash. It’s enough to make us wonder what other cool features in classic games were just kludgy hacks to get around potential problems.